Disk drives are information storage devices that use magnetic media to store data. The structure of a conventional disk drive is illustrated in FIG. 1. The disk drive comprises a housing 801 containing a set of magnetic disks 802 each having a surface on which a magnetic coating is provided for forming a plurality of concentric tracks (not shown). The disks 802 are mounted on a spindle motor 803 that selectively spins the disks 802. An actuator arm 804 is arranged in the housing 801 and is controlled by a voice-coil motor (VCM) 807 to drive a HGA 805 to fly above the disk 802, whereby a slider (or head) 806 carried by the HGA 805 is movable across the surface of the disk 802 from track to track for reading data from or writing data to the disk 802. In operation, a lift force is generated by aerodynamic interaction between the slider 806 and the spinning disk 802. The lift force is opposed by equal and opposite spring forces applied by a suspension of the HGA 805 such that a predetermined flying height above the surface of the spinning disk 802 is maintained over a full radial stroke of the actuator arm 804.
With the quickly increasing of the disk drive capacity and the improvement of the head seeking and settle times, the disk RPM (round per minute) becomes higher and higher for example 7,200, 10,000 and 15,000 RPM. With such a high rotation rate of the disk, an air flow created by rotation of the disk along the actuator arm and the suspension of the HGA to an air bearing surface (ABS) of the slider becomes faster and faster, this will create a big air turbulence due to interference of the air flow with the actuator arm and the suspension of the HGA, thereby causing vibration of the HGA. This will force the slider loaded thereon to be off-track and thus cause reading/writing errors of the disk drive.
In prior designs, since a structure in the actuator arm to restrict air flow is very small and its thickness has a limitation, it is easy for the air flow to go through a space between the actual arm/suspension and the disk surface to the ABS of the slider. This will still cause an air turbulence and vibration of the actuator arm/suspension.
Since the actuator arm and a load beam of the suspension are made by rigid material, a flexure of the suspension is easier to vibrate especially in a tail area thereof due to the air turbulence. Furthermore, since it is flexible and there is no limited support in its tail area, the vibration of the flexure in the tail area is more serious, which will affect the flying of the slider (or head) and cause an air turbulence and the slider off-track.
To solve the above-mentioned problems, U.S. Pat. No. 6,570,742 B2 teaches using a shield along a flow path to a leading edge of the slider to prevent the actuator arm and the HGA from flow induced vibration and excitation. Referring to FIGS. 2a and 2b, which illustrates the details of the U.S. Pat. No. 6,570,742 B2, an actuator arm 78 controls a HGA 76 and then a slider 84 flying above a disk 101. When the disk 101 is rotated by a spindle motor (not labeled), an air flow 94 is created, which flows around a surface of the disk 101 and is restricted by the actuator arm 78 and the HGA 76. The shield includes a finger 112 extending from a side edge (face to the air flow stream) of a tip 77 of the actuator arm 78. The finger 112 protrudes beyond sides of the actuator arm 78 and the HGA 76 to form a channel boundary to direct the turbulent air flow away from the HGA 76. Hence, a turbulent area 100 is shifted away from the HGA 76. That protects the actuator arm 78 and the HGA 76 from excitation and vibration, reduces the flying turbulence of the slider, and then reduces a possibility of the slider off-track and reading/writing errors of the disk drive. However, the shield restricting the air flow and changing the turbulent flow region will be easier to cause the slider vibration since the restrict force to the actuator arm is bigger. This will be easier to cause the slider vibration and the flexure vibration, especially in the tail area of the flexure, which will largely affect the slider flying and cause the slider to be off-track.
Referring to FIG. 3a, which shows a windage measurement data for the prior design, two peaks 301 at 10-14 kHz region illustrate a slider off-track displacement when the slider flying on the 7,200 RPM disk drive; in corresponding to FIG. 3b, two peaks 302 at 10-14 kHz region illustrate an air turbulence effect on the tail area of the flexure, which causes a flexure displacement in its tail area and thus the slider off-track displacement.
Thus, it is desired to provide a HSA with an air turbulence preventing structure for a HGA of a disk drive unit that can prevent sliders thereon from air flow turbulence induced vibration and excitation.